Vehicle lift



May 24, 1955 v. K. HOTT ETAL 2,703,936

VEHICLE LIFT Original Filed Sept. 29. 1948 s Sheets-Sheet 1 INVENTOR5. 0/v M ,e, #077 May 24, 1955 I. V. K. HOTT EI'AL Original Filed Sept. 29. 1948 YEHICLE LIFT 3 Sheets-Sheet 2 May 24, 1955' v. K. HOTT :rm.

VEHICLE LIFT s Sheets-Sheet 3 Original Filed Sept. 29. 1948 m m m United States Patent 8 Claims. (Cl. 1878.41)

This invention relates to vehicle lifts and more particularly to multipost lifts for busses, trucks, and other vehicles. The present invention is a division of the application filed by us September 29, 1948, Serial No.

51,668, and now Patent No. 2,681,077 granted June 15,

' One object of the invention is to provide a fluid operated vehicle lift comprising two lifting units to support and elevate the respective ends of a vehicle, at least one of said units including two lifting mechanisms to support the respective ends of one axle of the vehicle.

A further object of the invention is to provide such a lift having means for controlling the movements of the lifting mechanisms of the two units to maintain both the body and the axles of a vehicle thereon in substantially horizontal positions regardless of variations in the loads on the respective lifting mechanisms.

A further object of the invention is to provide a lifting unit comprising two lifting mechanisms to support the respective ends of one axle of a vehicle and. having means to maintain said end portions of said axle substantially in predetermined relative positions during the operation of the lifting unit.

A further object of the invention is to provide such a lifting unit having means controlled by the relative weights of the loads on the respective lifting mechanisms to cause said lifting elements to move at substantially the same speed regardless of variations in the relative weights of the loads thereon. V I

A further object of the invention is to provide such a mechanism which is simple in construction and positive in operation.

(Ether objects of the invention may appear as the mechanism is described in detail.

In the accompanying drawings Fig. l is a perspective view of a vehicle lift embodying the invention; Fig. 2 is a top plan view of one of the lifting mechanismsj Fig. 3 is a side elevation, partly in section, of the upper portion of the lifting mechanism of Fig.2; and Fig. 4 is a perspective view of a different vehicle lift embodying the invention.

In these drawings we have illustrated one embodiment of the invention, together with a modification thereof, and have shown the same as applied to a rnultipost lift, but it is to be understood that the lift as a Whole, as well as the several parts thereof, may take various forms without departing from the spirit of the invention.

In the form here shown the invention is applied to a two-post lift comprising two lifting units, and 16, spaced one from the other to support the respective ends of vehicle. The unit it) comprises a single lifting mechanism including a cylinder 11' mounted below a floor 12, a lifting element, or piston, 13 in said cylinder and a load supporting structure connected with the upper end of the lifting element and comprising parallel rails 14 on each of which is mounted a longitudinally adjustable axle engaging device 15. The second lifting unit, 16, comprises two lifting mechanisms spaced laterally one from the other to support the respective ends of the other axle of the vehicle. Each lifting mechanism of the second unit includes a cylinder 17 supported below the floor and a lifting element, or piston, 18 within the cylinder, and connected with the upper end of each lifting element 18 is a load supporting member 19, which in the present instance is adapted to engage and support the wheels at the respective ends of said other axle. As here shown the wheel engaging members 19 are concave and are supported in cavities 20 in the floor when the lifting elements are in their lowered positions. The cylinders 11 and 17 may be connected with any suitable source of propellent finial, such as oil, and a control mechanism is interposed between the source of fluid and the respective cylinders. In the present instance the control mechanism is the same as the mechanism shown in our above mentioned application for patent and comprises a valve mechanism, not here shown, enclosed in a casing 21 and connected by a conduit 22 with the cylinder 11 and by a conduit 23 with the cylinders 17, the conduit 23 being branched, as shown at 230, to connect the same with the two cylinders 17. The conduits 22 and 23 are connected through the valve mechanism with a source of fluid under pressure, such as the tank 24, and the valve mechanism is controlled by an actuating member 25 to regulate the flow of fluid to the cylinders of the two units so as to maintain the vehicle in a substantially horizontal position regardless of differences in the weights on the two units. Either unit, 10 or 16, may support either the. front end or the rear end of the vehicle and for present purposes the unit 10 may be considered as the front unit and the unit 16 may be considered as the rear unit.

It sometimes happens that the load on the lifting unit 16 will be unevenly divided between the lifting elements 18 and that the-lifting element having the lighter load will tend to move upwardly at a speed greater than the speed at which the other lifting element moves. For the purpose of causing the two lifting elements to move at substantially uniform speeds an equalizing device is interposed between the two lifting elements. This equalizing device may take various forms but as here shown it comprises tubular guides 26 rigidly supported on the respective cylinders 17 and extending lengthwise thereof on adjacent sides of the cylinders. Slidably mounted in each tubular guide is a bar 27 provided with rack teeth 28 and'rigidly connected at its upper end with the corresponding lifting element 18, as by rigidly securing the same to a projecting part of the wheel supporting member 19. Rotatably mounted in each guide 26, adjacent the upper end thereof, is a short shaft 29 to which is rigidly secured a pinion 34} which meshes with the stationary rack bar 27 and is thus rotated by the vertical movement of the lifting element. The adjacent ends of the two shafts 29 are connected one with the other, for.

rotation in unison, by a shaft 31 which is connected with the respective shafts 29 by universal joints 32. Inasmuch as the pinions of the two lifting mechanisms 17 of this unit are thus caused to rotate in unison it will be obvious that if one lifting element tends to move at a speed greater than the speed of movement of the other lifting element a portion of the force exerted on the first mentioned lifting element will be transmitted through the pinions to the last mentioned lifting element, and the two lifting elements will thereby move at the same speed at all times regardless of any variation in the relative weights of the loads thereon.

In Fig. 4 there is illustrated an application of the invention to a vehicle lift in which one of the lifting units is bodily movable toward and from the other lifting unit. The rear or two cylinder unit 33 is of the same construction as that above described but the front or single cylinder unit 34 is adjustable lengthwise of the lift toward and from the rear unit. As there shown the lifting mechanism of the unit 34 comprises a cylinder 35 and a lifting element 36 having on its upper end an axle supporting structure 37. The cylinder 35 and there fore the unit as a whole is supported on a plate 38 which is slidably mounted on the floor 39 and constitutes a closure for the open end of a pit 40. The plate may be supported in any suitable manner and as here shown it is mounted on a carriage 41 which is provided at its sides with rollers 42 which travel on tracks 43 mounted on the side walls of the pit. The fluid supply conduit 44 is made extensible, as by providing it with pivotally connected sections 45. The plate 38, and therefore the lifting unit 34, may be adjusted lengthwise of the pit in any suitable manner. In the present instance the plate is provided with a series of holes 46 through which an actuating rod may be inserted and engaged with another series of holes 47 in a fixed part of a structure beneath the edge of the plate and the plate thus moved step by step in either direction. The fluid is supplied to the two lifting units by the conduit 44 and by a second conduit 48 which is branched for connection with the two cylinders of the unit 33.

Thus the unit 34 may be adjusted lengthwise of the lift to accommodate it to vehicles having wheel bases of different lengths and the control of the flow of fluid to the two units may be controlled by a valve mechanism in the casing 50 in the manner above described to maintain the load supporting structures 37 and 19 at substantially the same distance above the floor, and the W0 lifting elements of the unit 33 are automatically adjusted by variations in the weights of the loads thereon to cause the same to move at substantially the same speeds.

Thus it would be apparent that by regulating the supply of fluid to the two lifting units the lifting elements 10 and 16, or 34 and 33, may be so controlled as to maintain the vehicle in a substantially horizontal position, and any variations in the weights of the loads on the load supporting elements of the unit 16, or 33, will automatically equalize the movements of those supporting elements to prevent the tilting of the axle supported by those members.

While we have shown and described certain embodiments of our invention we wish it to be understood that we do not desire to be limited to the details thereof as various modifications may occur to a person skilled in the art.

Having now fully described our invention, what we claim as new and desire to secure by Letters Patent is:

1. A lifting unit comprising two laterally spaced fluid operated mechanisms, each mechanism including an upright cylinder, a piston in said cylinder, a load supporting member connected with said piston, a downwardly ex tending toothed bar connected with said load supporting member for movement therewith, and a pinion rotatably supported on said cylinder and meshing with said toothed bar, a shaft interposed between the pinions of the two mechanisms, universal joints connecting said shaft with the respective pinions, and means for supplying propellent fluid to said cylinders simultaneously and at sub- Y stantially equal pressures.

2. A lifting unit comprising two laterally spaced fluid operated mechanisms, each mechanism including an upright cylinder, a piston in said cylinder, a load supporting member connected with said piston, a guide secured to and extending lengthwise of said cylinder, a rack bar connected with said load supporting member and movable thereby in said guide, and a pinion rotatably mounted on said guide and meshing with said bar, a shaft interposed between the pinions of the two mechanisms, uni versal joints connecting said shafts with respective pinions, and means for supplying propellant fluid to said cylinders simultaneously and at substantially equal pressures.

3. A fluid operated lift comprising two lifting units spaced one from the other to support the respective ends of a vehicle, one of said units comprising a single cylinder, a piston in said cylinder, and a structure carried by said piston to support one axle of said vehicle,

the other of said units including two cylinders spaced laterally one from the other, a piston in each cylinder,

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and separate members connected with said pistons to support the respective ends of the other axle of said vehicle, means for.simultaneously supplying propellent fluid to the cylinders of both units including means for regulating the flow of fluid to the cylinders of the two units to maintain said vehicle substantially in a horizontal position, and means controlled by the relative Weights of the loads on the pistons of the two cylinder unit to prevent movement of the last mentioned axle about a transverse axis.

4. A fluid "operated lift comprising two lifting units spaced one from the other to support the respective ends of a vehicle, one of said units comprising a single cylinder, a piston in said cylinder, and a structure carried by said piston to support one axle of said vehicle,

the other of said units including two cylinders spaced laterally one from the other, a piston in each cylinder, and separate members connected with said pistons to support the respective ends of the other axle of said vehicle, means for simultaneously supplying propellent fluid to the cylinders of both units including means for regulating the flow of fluid to the cylinders of the two units to maintain said vehicle substantially in a horizontal position, an equalizing device interposed between the pistons of said two cylinder unit and drivingly connected with both pistons to cause said pistons to move at substantially the same speed.

5. A fluid operated vehicle lift comprising two units spaced one from the other to support the respective ends of a vehicle, one of said units comprising a cylinder in said piston and a load supporting structure on said piston, means for supporting said unit for movement lengthwise of said vehicle with relation to the other of said units, the other of said units comprising two cylinders spaced laterally one from the other, a piston in each cylinder, and load supporting members separatelysupported on said pistons, means for supply- .ing propellent fluid to the cylinders of both units and for regulating the flow of fluid to said units to maintain said vehicle substantially horizontal in all positions of said movable unit, and a device interposed between and drivingly connected with the pistons of said two cylinder unit to maintain the load supporting members of said unit substantially in horizontal plane regardless of variations in the weight of the loads on the respective pistons.

6. A fluid operated lift comprising tripodal lift means, each of said means comprising a single cylinder, at piston in said cylinder, a vehicle engaging structure carried by the piston for supporting a portion of a vehicle, a pair of said lift means being spaced laterally one from the other, an equalizing means for causing only said pair of lift means to move in unison, a common source of fluid for actuating all of said lift means simultaneously, and means interposed between said source and the lift means for regulating the relative flow of fluid between said pair of lift means and the other lift means.

7. A fluid operated lift according to claim 6, wherein the pair of lift means supports one end of the vehicle, and the other lift means supports the other end of the vehicle.

8. A fluid operated lift according to claim 6, wherein the distance between said pair of lift means and the other lift means may be adjusted to accommodate vehicles of differing lengths.

References Cited in the file of this patent UNITED STATES PATENTS 

